To get this out of the way, I completely realise that making spears a potential finesse weapon would be a deviation from D&D 5e, but I think where it is necessary, makes logical sense or adds interesting possibilities for players and roleplaying, it is a good thing to diverge from the foundational ruleset.
In my opinion, spears should have the Finesse property, meaning that they can be used with Dex instead of Str. For once it makes sense logically. Normal spears, especially if wielded with two hands, are light, pretty versatile and very fast weapons, making them much more fitting for being Dex based than some others of the finesse weapons (especially Scimitars). More importantly though, it would give interesting new ways for creating and roleplaying characters. Many spear users in fantasy can be classified as Dex based (Oberyn Martel being probably the most prominent) and it would be cool to be able to play similiar characters. Dex based fighters, rogues and especially rangers would get an interesting and thematically fitting weapon choice, without any real downside or game breaking consequence. The only negative aspect to this I could see, is that it could be a bit weird seeing a rogue sneaking through buildings with a spear, although something similiar could be said about sneaking in full medium armor with a big longbow on the back.
What are your opinions on this?